Constructed from stainless steel and anodised aluminium these are packaged with O-rings to stabilise the barrel at either end (in addition to providing a superior air seal). They also include a hop rubber into the bargain!
Inner diameter is 6.03mm
The 550mm barrel is intended for the M16A1, M18A2, M16VN, AUG and M249 extended.
currently not available for this item